The purpose of this experiment was to evaluate the contribution of epiphytic microbiota on alfalfa (AL), oat (OT), and red clover (RC) to ensiling characteristics and bacterial community diversity of oat. With the irradiation of γ-ray, sterile OT (~233 g/kg dry matter (DM)) was inoculated by sterile water (STOT), epiphytic microbiota from OT (OTOT), AL (OTAL) and RC (OTRC), respectively. Triplicate silage-bags for each treatment were sampled after different days (1, 3, 7, 15, 30 and 60) of fermentation, respectively. Similar chemical compositions were found between fresh oat and STOT. Lower (P < 0.05) contents of ammonia nitrogen (NH3-N) and higher (P < 0.05) accumulation of lactic acid were found in OTAL compared with OTRC and OTOT on day 3. The greatest (P < 0.05) NH3-N, acetic acid concentrations and pH and the lowest (P < 0.05) concentration of lactic acid were found in OTRC on day 60. After 3 days of ensiling, Lactobacillus accounted for a big proportion in OTAL and OTOT, and Hafnia-Obesumbacterium was predominant in OTRC. The bacterial communities in OTAL and OTOT had lower (P < 0.05) abundances of ‘Genetic Information Processing’ than OTRC after 3 days. Overall, the composition, diversity, and activity of epiphytic microbiota can notably influence the ensiling characteristics of forage oat. The lactic acid bacteria (hetero-fermentative type) and Enterobacteriaceae species played an important role in producing ethanol contents during the ensiling of forage oat.

Cowvine (Ipomoea lonchophylla J.M. Black) is a native and widely spread summer broadleaf weed in Australia. It contains glycoresins, which are toxic to livestock. However, limited information is available on seed germination ecology and growth phenology of this species. A series of experiments were conducted to determine the response of I. lonchophylla to different environmental conditions. Results showed that the primary dormancy exhibited by I. lonchophylla is due to the physical impediment of the hard seed coat. The seed germination percentage was the highest at the constant temperature of 27 C and alternating temperatures of 35/25 C. Germination of I. lonchophylla was not stimulated by light, suggesting that this species is non-photoblastic. Ipomoea lonchophylla germination was intolerant of a medium to high level of salt stress, and germination was completely inhibited at 250 mM NaCl. The emergence of I. lonchophylla was not restricted by seeding depth up to 8 cm, but only 5% emergence was recorded when seeds were planted at a 16-cm depth. The germination percentage was also drastically reduced by 90% to 100% after exposure to either 3 mo in silage, 48-h digestion in steers, or silage plus digestion treatments. The growth and reproductive phenology of I. lonchophylla was affected by emergence time. Plants that emerged in late spring (November 15) were able to produce more berries per plant than those that emerged in midsummer (January 15) in southern New South Wales. Information gained in our study concerning high soil salinity, ensiling, and digestion will help to develop more sustainable and effective integrated weed management strategies for controlling and reducing the spread of this weed.

The bacterial community is important for shaping the fermentation characteristics of silage. This study aimed to investigate the fermentation characteristics, bacterial community and predicted functional characteristics of red clover (Trifolium pratense L.) silage. First-cutting red clover was collected at the early bloom stage, wilted for 5 h and then ensiled in 10 litre-capacity silos. Triplicate silos were sampled after 1, 3, 7, 15, 30 and 60 days of ensiling, respectively. The bacterial communities on days 3 and 60 were assessed through high-throughput sequencing technology, and 16S rRNA-gene predicted functional characteristics were analysed based on the KEGG using Tax4Fun. After 60 days of ensiling, red clover silage was fermented well, as indicated by high lactic acid (~77.3 g/kg DM), and low concentrations of butyric acid (~3.73 g/kg DM) and ammonia nitrogen (~55.0 g/kg TN). During the initial stage of ensiling, fructose and glucose were more preferred than sucrose for microbes. The predominant genus Lactococcus (0.542) on day 3 was replaced by Lactobacillus (0.553) on day 60. The metabolism of amino acids, energy, cofactors and vitamins was inhibited, while the metabolism of nucleotides and carbohydrates was enhanced after ensiling. High-throughput sequencing technology combined with 16S rRNA gene-predicted functional analyses revealed the differences during the early and late stages of red clover silage not only for distinct bacterial compositions but also for specific functional traits. Our results could provide a comprehensive insight into bacterial community and their functional profiles to further improve the silage quality.

An experiment was carried out to examine the effects of offering beef steers grass silage (GS) as the sole forage, lupins/triticale silage (LTS) as the sole forage, a mixture of LTS and GS at a ratio of 70:30 on a dry matter (DM) basis, vetch/barley silage (VBS) as the sole forage, a mixture of VBS and GS at a ratio of 70:30 on a DM basis, giving a total of five silage diets. Each of the five silage diets was supplemented with 2 and 5 kg of concentrates/head/day in a 5 × 2 factorial design to evaluate the five silages at two levels of concentrate intake and to examine possible interactions between silage type and concentrate intake. A total of 80 beef steers were used in the 122-day experiment. The GS was well preserved while the whole crop cereal/legume silages had high ammonia-nitrogen (N) concentrations, low lactic acid concentrations and low butyric acid concentrations For GS, LTS, LTS/GS, VBS and VBS/GS, respectively, silage DM intakes were 6.5, 7.0, 7.2, 6.1 and 6.6 (s.e.d. 0.55) kg/day and live weight gains were 0.94, 0.72, 0.63, 0.65 and 0.73 (s.e.d. 0.076) kg/day. Silage type did not affect carcass fatness, the colour or tenderness of meat or the fatty acid composition of the intramuscular fat in the longissimus dorsi muscle.

An experiment was carried out to examine the effects of offering beef cattle five silage diets. These were perennial ryegrass silage (PRGS) as the sole forage, tall fescue/perennial ryegrass silage (FGS) as the sole forage, PRGS in a 50:50 ratio on a dry matter (DM) basis with lupin/triticale silage (LTS), lupin/wheat silage (LWS) and pea/oat silage (POS). Each of the five silage diets was supplemented with 4 and 7 kg of concentrates/head/day in a five silages × two concentrate intakes factorial design. A total of 90 cattle were used in the 121-day experiment. The grass silages were of medium digestibility and were well preserved. The legume/cereal silages had high ammonia N, high acetic acid, low lactic acid, low butyric acid and low digestible organic matter concentrations (542, 562 and 502 g/kg DM for LTS, LWS and POS, respectively). Silage treatment did not significantly affect liveweight gain, carcass gain, carcass characteristics, the instrumental assessment of meat quality or fatty acid composition of the M. longissimus dorsi muscle. In view of the low yields of the legume/cereal crops, it is concluded that the inclusion of spring-sown legume/cereal silages in the diets of beef cattle is unlikely to be advantageous.

Type D bovine botulism outbreaks associated with poultry litter are increasingly reported in European countries, but the circumstances of exposure to Clostridium botulinum toxins remain unclear. In spring 2015, a large type D/C bovine botulism outbreak affected a farm with dairy and poultry operations. Epidemiological and laboratory investigations strongly suggest that the outbreak was caused by feeding cattle with insufficiently acidified grass silage that was contaminated by type D/C C. botulinum spores. The source of the spores remains unclear, but could have been a stack of poultry litter stored in the grass silage pasture before harvesting. The presence of putrefied poultry carcasses mixed in with the litter is relatively unlikely considering the careful daily removal of poultry carcasses. These findings reinforce the importance of proper ensiling of feed materials and highlight the need for safe disposal of poultry litter, even in the case of good management of poultry deadstock, in order to prevent bovine botulism.

Controlled traffic farming (CTF) systems aim to reduce soil compaction by restricting machinery field traffic to permanent traffic lanes. Grass-clover silage production is generally associated with intensive field traffic, resulting in reduced silage clover content. If CTF can increase yield and clover content in grass-clover leys, this would reduce the need for grain and expensive protein concentrate in dairy cow feed rations. A mixed integer programming model was developed to evaluate the potential profitability of CTF in a dairy farm context. Existing field trial data were used to calculate the expected yield outcome of CTF, based on reductions in trafficked area. The results revealed that CTF increased profitability by up to €50/ha. Total machinery costs are likely to increase on converting to CTF, but variable machinery costs are likely to decrease.

The influence of the potential methane reducer, fumaric acid (FA), on ruminal parameters, the rumen wall and organ weights was investigated in a long-term study with growing bulls. In all, 20 bulls were fed with maize or grass silage as roughage, and with concentrate with or without 300 g FA per animal and day during the whole fattening period. After slaughtering, the organs were weighed and blood serum was analysed for glucose, β-hydroxybutyric acid (BHB) and non-esterified fatty acid concentration. The ruminal fluid was analysed for short-chain fatty acids, ammonia-N and the microbial community via single strand conformation polymorphism analysis. The rumen wall was examined histopathologically and results were graded as ‘no visible lesions’, ‘few inflammatory infiltrates’, ‘some inflammatory infiltrates’ or ‘several inflammatory infiltrates’. In addition, the dimensions of the rumen villi were measured. The FA supplementation decreased the serum BHB concentration and the butyric acid concentration in the ruminal fluid. The microbial community in the ruminal fluid was not influenced by FA. An interaction between FA and silage type was observed for the inflammation centres counted in the villous area of rumen papillae. This interaction was also observed in the length and surface of the rumen villi. Rumen villi results show that the influence of FA depends on the roughage used in the diet.

The concentration of crude protein in grazed New Zealand pasture is typically in excess of 200 g/kg DM, which exceeds the requirement of the dairy cow and is reflected in elevated levels of daily urinary nitrogen (N) excretion, estimated to average 262 g N/head or 751 kg N/ha. This has adverse environmental consequences, including leaching of nitrate from soil into water courses and atmospheric emissions of nitrous oxide. Problems associated with pasture as the sole feed for dairy cows include weight loss in early lactation, poor fertility and reduced lactation length. Low-protein supplements can reduce N excretion rates and increase N use efficiency. A simple feeding strategy is proposed in which pasture is supplemented with maize or whole-crop wheat silage at 5 kg DM/cow per day from the start of the pre-calving dry period on winter run-off pasture to 100 days post-calving, and from 250 days post-calving to the end of lactation. The expected response, at an assumed substitution rate of 0.7 kg decrease in pasture intake per kg silage DM, is an increase in metabolisable energy of 10 to 15 MJ/cow/day, equivalent to 33 to 48 g milk solids (MS)/kg DM of supplement. This strategy is expected to result in significantly lower urinary N excretion by the cow. Actual responses in daily milk output, from published experiments where grazing stocking rates were increased to take account of reduced herbage intake, ranged from 50 to 100 g MS/kg DM of supplement. Other benefits include early lactation bodyweight maintenance, higher percentage of cows calved which are pregnant at 150 days in milk and increased lactation period. Constraints for farmers to implement such changes include cost of silage, value of milk sold, failure to integrate forage maize or wheat in rotational cropping with pasture, and the relatively poor aerobic stability of maize and whole-crop wheat silages.

Two experiments studied the effects of dietary chicory against gastrointestinal nematodes in cattle. In Experiment (Exp.) 1, stabled calves were fed chicory silage (CHI1; n = 9) or ryegrass/clover hay (CTL1; n = 6) with balanced protein/energy intakes between groups. After 16 days, all calves received 10 000 Ostertagia ostertagi and 66 000 Cooperia oncophora third-stage larvae (L3) [day (D) 0 post-infection (p.i.)]. In Exp. 2, calves were assigned to pure chicory (CHI2; n=10) or ryegrass/clover (CTL2; n = 10) pastures. After 7 days, animals received 20 000 O. ostertagi L3/calf (D0 p.i.) and were moved regularly preventing pasture-borne infections. Due to poor regrowth of the chicory pasture, CHI2 was supplemented with chicory silage. At D40 p.i. (Exp. 1) and D35 p.i. (Exp. 2) calves were slaughtered for worm recovery. In Exp.1, fecal egg counts (FEC) were similar between groups. However, O. ostertagi counts were significantly reduced in CHI1 by 60% (geometric mean; P < 0·01), whereas C. oncophora burdens were unaffected (P = 0·12). In Exp. 2, FEC were markedly lowered in CHI2 from D22 p.i onwards (P < 0·01). Ostertagia ostertagi adult burdens were significantly reduced in CHI2 by 66% (P < 0·001). Sesquiterpene lactones were identified only in chicory (fresh/silage). Chicory shows promise as an anti-Ostertagia feed for cattle and further studies should investigate its on-farm use.

Most often, farmers consider red clover an unattractive forage because of its low ensilability. Nevertheless, several in vivo and in vitro experiments also showed advantages of red clover silages such as decreased rumen biohydrogenation of polyunsaturated fatty acids. This has been attributed to a possible protective role of protein-bound phenols, with polyphenol oxidase playing a key role in their formation. This enzyme is active in red clover, but not in other green forages, such as, for example, perennial ryegrass. Therefore, the aim was to study the lipid metabolism within red clover/ryegrass mixtures in lab scale silages and during in vitro rumen batch incubations. Ensilability of red clover increased with higher proportions of ryegrass in the silage mixture. However, the lipid-protecting mechanism of red clover does not seem to occur in the co-ensiled ryegrass as lipolysis of polar lipids linearly increased with increasing proportions of ryegrass (86.0%, 91.6%, 89.9%, 93.1% and 95.6% in 60-day-old silages with 100/0, 75/25, 50/50, 25/75 and 0/100 red clover/ryegrass, respectively). Rumen lipolysis and biohydrogenation of C18:3n-3 and C18:2n-6 were negatively related to red clover proportions in the silage mixtures. The lipid-protective mechanism in red clover silages is confirmed, but it seems not to be transferred to lipids in co-ensiled forages.

Late blowing, caused by the outgrowth of clostridial spores present in raw milk and originating from silage, can create considerable product loss, especially in the production of hard and semi-hard cheeses. The conventional method for the isolation of Clostridium spp. from cheeses with late-blowing symptoms is very complicated and the identification of isolates is problematic. The aim of this work was the development of a multiplex PCR method for the detection of the main dairy-related clostridia such as: Cl. beijerinckii, Cl. butyricum, Cl. sporogenes, Cl. tyrobutyricum. Samples derived from silage, raw milk and hard cheese were analysed by the most probable number (MPN) enumeration. Forty-four bacterial strains isolated from gas positive tubes were used to check the reliability of the multiplex PCR assay. The specificity of the primers was tested by individually analysing each primer pair and the primer pair combined in the multiplex PCR. It was interesting to note that the samples not identified by the multiplex PCR assay were amplified by V2–V3 16S rRNA primer pair and the sequencing revealed the aligned 16S rRNA sequences to be Paenibacillus and Bacillus spp. This new molecular assay provides a simple promising alternative to traditional microbiological methods for a rapid, sensitive detection of clostridia in dairy products.

The effect of the forage source on ruminal fermentation in vitro was investigated for fine (F) and coarse (C) milled diets, using a modified Hohenheim gas production test and a semi-continuous rumen simulation technique (Rusitec). It was hypothesised that the replacement of maize silage by grass silage might lead to associative effects and that interactions related to particle size variation could occur. Five diets with a maize silage to grass silage ratio of 100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100 differed in their content of CP and carbohydrate fractions, as well as digestible crude nutrients, derived from a digestibility trial with wether sheep. For in vitro investigations, the diets were ground to pass a sieve of either 1 mm (F) or 4 mm (C) perforation. Cumulative gas production was recorded during 93 h of incubation and its capacity decreased with increasing proportion of grass silage in the diet. Across all diets, gas production was delayed in C treatments compared with F treatments. Degradation of crude nutrients and detergent fibre fractions was determined in a Rusitec system. Daily amounts of NH3-N and short-chain fatty acids (SCFA) were measured in the effluent. Degradation of organic matter (OM) and fibre fractions, as well as amounts of NH3-N, increased with stepwise replacement of maize silage by grass silage. Degradability of CP was unaffected by diet composition, as well as total SCFA production. In contrast to the results of the gas production test, degradation of OM and CP was higher in C than in F treatments, accompanied by higher amounts of NH3-N and SCFA. Interactions of silage ratio and particle size were rare. It was concluded that the stepwise replacement of maize silage by grass silage might lead to a linear response of most fermentation characteristics in vitro. This linear effect was also supported by total tract digestibility data. However, further investigations with silages of variable quality seem to be necessary.

The objective was to investigate the effect of variation in forage source and feed particle size of a diet, including interactions, on the amount and the composition of microbial crude protein (CP) in a semi-continuous culture system (Rusitec). Different microbial CP fractions were compared. Five diets with mean forage proportion of 0.88 and different maize silage to grass silage ratios (100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100) were used. Diets were ground through sieves with a pore size of either 1 or 4 mm, matching the particle size of fine (F) and coarse (C), respectively. Diets were characterised by increasing concentrations of CP and fibre fractions, and decreasing concentrations of starch with ascending inclusion rates of grass silage. Microbial mass was isolated from feed residues after incubation from the liquid phase of the fermenter and from the liquid effluent. The amount of synthesised microbial CP was determined on the basis of 15N balance. It increased quite linearly by the stepwise replacement of maize silage by grass silage, and was higher in C treatments compared to F treatments. Efficiency of microbial CP synthesis (EMPS) was improved from 29 to 43 mg microbial N/g degraded organic matter (OM) by increasing the proportion of grass silage in the diet, but was unaffected by particle size. The N content as well as the profiles of amino acids of the three microbial fractions was affected by diet composition and particle size. The ratio of solid- to liquid-associated microbes was affected by diet composition and feed particle size. The amount and EMPS seemed to be improved by degradation of OM from grass silage and an increasing availability of N. Moreover, the results of this study indicated a shift in the composition of the microbial community caused by variation in forage composition and feed particle size.

Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO’s lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid encapsulation in protein–phenol complexes would lead to an effective protection of lipids against ruminal biohydrogenation. From several studies it has also become apparent that the degree of PPO activation could influence the mode and degree of protection. In conclusion, this review demonstrates that protein-bound phenols and encapsulation in protein–phenol complexes, induced by PPO-mediated diphenol oxidation, could be of interest when aiming to protect lipids against pre-ruminal and ruminal degradation.

The first reported bovine botulism outbreak in Finland is described. Nine out of 90 cattle on a dairy farm died after being fed non-acidified silage contaminated by animal carcasses. Type C botulinum neurotoxin gene was detected in one heifer by polymerase chain reaction (PCR) and the neurotoxin was detected by the mouse bioassay. Clostridium botulinum type C was isolated from liver samples. The isolated strain was identified with amplified fragment length polymorphism (AFLP) analysis as group III C. botulinum. To our knowledge, this is the first time that a type C bovine botulism outbreak has been diagnosed by PCR and confirmed by subsequent isolation and AFLP identification of the disease strain. The importance of the acidification process in silage production to inhibit C. botulinum toxin production in silage and thus to prevent further botulism outbreaks is emphasized. Nevertheless, preformed toxin in the carcass is not destroyed by acid.

Replacing grass silage with maize silage results in a fundamental change in the ratio of structural to non-structural carbohydrates with commensurate changes in rumen fermentation patterns and nutrient utilisation. This study investigated the effects of feeding four forage mixtures, namely grass silage (G); 67 g/100 g grass silage + 33 g/100 g maize silage (GGM); 67 g/100 g maize silage + 33/100 g grass silage (MMG); maize silage (M) to four ruminally and duodenally canulated Holstein Friesian steers. All diets were formulated to be isonitrogenous (22.4 g N/kg DM) using a concentrate mixture. Dietary dry matter (DM) and organic matter (OM) digestibility increased with ascending maize silage inclusion (P < 0.1) whereas starch and neutral detergent fibre digestibility declined (P < 0.05). Ratio of non-glucogenic to glucogenic precursors in the rumen fluid increased with maize silage inclusion (P < 0.01) with a commensurate reduction in rumen pH (P < 0.05). Mean circulating concentrations of insulin were greatest and similar in diets MMG and GGM, lower in diet M and lowest in diet G (P < 0.01). There were no effects of diet on the mean circulating concentration of growth hormone (GH), or the frequency, amplitude and duration of GH pulses, or the mean circulating concentrations of IGF-1. Increasing levels of DM, OM and starch intakes with the substitution of grass silage with maize silage affected overall digestion, nutrient partitioning and subsequent circulating concentrations of insulin.

Tanniferous forage plants can have beneficial effects on ruminant productivity and health (improved protein supply, bloat safety and antiparasitic properties). However, condensed tannins can also lower palatability, voluntary feed intake and digestibility. The aim of our interdisciplinary project was to generate basic knowledge on plant management, feed palatability and the antiparasitic properties of tanniferous forage plants for their practical application in agronomy, focusing on their usefulness in controlling gastrointestinal nematodes in organic farming. We found that Onobrychis viciifolia (sainfoin), Lotus corniculatus (birdsfoot trefoil) and Cichorium intybus (chicory) were suitable for cultivation under the given temperate climatic conditions, whereas Lotus pedunculatus (big trefoil) was soon outcompeted by unsown species. Growing the tanniferous plant species in a mixture with Festuca pratensis (meadow fescue) rather than in a monoculture had the advantage of increasing total dry matter (DM) yield (especially in the case of tanniferous legumes) and of reducing the DM proportions of unsown species. However, due to dilution by non-tanniferous F. pratensis, the tannin concentrations of mixtures were clearly lower and the seasonal fluctuations in tannin concentrations greater than that of monocultures. Across species, tannin concentrations were highest for O. viciifolia, followed by L. corniculatus and very low for C. intybus. Palatability of all tanniferous forages was comparable to that of a ryegrass/clover mixture when fed as dried forage and, when offered as silage, palatability of O. viciifolia was clearly superior to that of the respective ryegrass/clover control. Administration of dried or ensiled O. viciifolia reduced parasite egg counts in feces of lambs co-infected with the gastrointestinal nematode species Haemonchus contortus and Cooperia curticei. We conclude that O. viciifolia is the most promising among the tested tanniferous forage plant species due to its suitability for cultivation, its high tannin concentration, its high palatability and its antiparasitic activity even in dried or ensiled form.

Whole-plant winter cereals could be of great interest if used as silages for ruminant feeding as opposed to summer crops in that they would spare water resources or valorize low-input management. This study aimed to compare the feeding value of rye, barley, wheat (two genotypes) and triticale (six genotypes). The cereals were sown in October and harvested as silage in June. Forages were offered to Texel castrated sheep in order to evaluate the organic matter digestibility (OMd). The OMd of the wheat cultivars was higher (61.6%, P<0.05) than those of barley (57.2%) and rye (54.7%) but no different from that of triticale (60.6%). Within the triticale genotypes, OMd ranged from 54.7 to 62.3%. The presence of rough barbs should explain the relatively low intake of the cereals with the exception of wheat. Winter cereals provide good-quality forage for feeding ruminants. Wheat has a higher nutritional value than barley and rye and a wide variability for digestibility seems to exist within the triticale cultivars. Such variability in a species known for its ability to be cropped under limiting conditions should be explored in much greater depth as it could result in providing farmers with genotypes of good quality with an acceptable yield at a lower cost.

To study the effect of feeding silages with different botanical composition, on rumen and lamb fat, 30 male lambs were assigned to five different silage groups for 11 weeks: botanically diverse silage (BDS); white clover silage (WCS); red clover silage (RCS), intensive English ryegrass silage (IRS) and crushed linseed and maize silage (MSL). Besides the silages, animals received organic wheat and barley and the MSL group additionally received bicarbonate (15 g/day). Silages were sampled when the bales were opened and analysed for fatty acid (FA) content and chemical composition. At slaughter, ruminal contents were sampled and 24 h after slaughter, longissimus muscle and subcutaneous (SC) fat were sampled. All samples were analysed for FA composition. The MSL group ingested the highest amount of FA (35.8 g/day v. 13.5, 19.4, 17.2 and 30.4 g/day for MSL v. BDS, WCS, RCS and IRS, respectively) and the sum of the major polyunsaturated FA, C18:2 n-6 and C18:3 n-3, was similar for groups BDS, WCS, RCS and MSL (61.3 g/100 g, 62.3 g/100 g, 62.3 g/100 g, 63.7 g/100 g of FA methylesters (FAME), respectively), while group IRS ingested higher proportions of these FA (74.5 g/100 g of FAME). Rumen data showed that animals fed BDS presented higher proportions of biohydrogenation intermediates, particularly C18:1 t11 and CLA c9t11, suggesting partial inhibition of rumen biohydrogenation. In the MSL group, the content of C18:3 n-3 in the rumen was highest, most probably due to reduced lipolysis and hence biohydrogenation through the combined effect of esterified C18:3 n-3 and seed protection. Additionally, C18:3 n-3 proportions were higher in rumen contents of RCS animals compared with WCS animals, which could be due to the activity of the polyphenol oxidase enzyme in the RC silages. Proportions of C18:3 n-3 were similar between treatments both for SC and intramuscular (IM) fat, whereas CLA c9t11 content was higher in the SC fat of BDS animals and lower in the IM fat of IRS animals compared with the other forage groups. No differences were found for C20:4 n-6, C20:5 n-3, C22:5 n-3 and C22:6 n-3 in the IM fat of the animals. Nevertheless, indices for desaturation and elongation activity in muscle of BDS animals suggest some stimulation of the first three steps of desaturation and elongation (Δ6-desaturase, elongase and Δ5-desaturase) of long-chain FA.